Light-sensitive apparatus



May 24, 1932- T. A. E. BELT 1,860,169

LIGHT SENSITIVE APPARATUS Filed Aug. 6. 1928 Invent r I Thomas AE. Belt,

( by 7 His Attorney.

Patented May 24, 1932 UNITED STATES THOMAS A. E. BELT, OF SGHENEGTADY,NEW YORK, ASSIGNOR T GENERAL ELECTRIC COMPANY, A CORPORATION 011 NEW YOBK LIGHT-SENSITIVE APPARATUS Application filed August 6, 1928. 'SerialNo. 297,896.

The present invention relates to light-sensitive apparatus and inparticular to arrangements for controlling circuits in response tovariations of light. When employing photoelectric cells or other formsof light-sensitive devices for actuating control circuits in response tochanges in the intensity of a light source, it has been customary. toemploy several stages of amplifi- 0 cation in order to derive sufiicientoutput current. The, presence of these amplifiers, particularly those ofthe thermionic type, renders the system somewhat complicated and to somedegree unreliable from an oper- 1a ation standpoint. These disadvantagesare accentuated in case the system is located in places which are eitherremote Ol' otherwise not readily accessible, where tubes for replacementare not readily obtainable or where interruptions of the service areparticularly objectionable, as in traiiic signaling and the like. Inaccordance with one feature of the present invention, there is provided5 a high power amplifying circuit which is rendered operable by means ofan electrical impulse derived from the light-sensitive apparatus or insome cases, by means of the lack of such impulse, to produce a currentflow sufficient for operating directly a large current relayforming'part of the circuit or circuits to be controlled, without theaid of additional amplification. Such control circuits have multifarioususes, for example, lighting signboards at dusk or energizing signallights in response to the illumination of the photo-cell bythe headlightof a moving vehicle. I The improved system contemplates anamplifyingdevice in which no filamentary D or other fragile form ofelectron source is necessary although it, is to be distinctly understoodthat my invention includes am plifiers and electron emitters of allkinds. According to another feature of my invention, the variousapparatus employed is adapted to be energized directly by alternatingcurrent of ordinary voltage and frequency, thus facilitating theirinstallation on existing lighting circuit lines. One of the objects ofmy invention is to provide a large current carrying'circuit of simpleand rugged; character which may be energized from an alternating currentsource and may be effectively controlled by a var able light source.Other objects-and features will be apparent by reference to thespecification taken in connection with the accompanying drawing whichillustrates a preferred embodiment. 7

Referring to the figure, numeral 1 designates a t insformer, thesecondary of which consists or two perons or sections 2 and 3; thewinding 2 provides energy for light-sensitive device 4 which maycomprise a photocell of ordinary type, i. e., provided with aphoto-sensitive cathode which is adapted to be activated by a lightsource (not shown). The circuit A contains in addition to the device 4,an output transformer 5 with ad justable taps to give any desired turnratio, as shown. The wii ling 3 serves to energize an alternating Cullnt relay 6 and an ionization or are device 7 which has in seriestherewith the secondary winding of transformer 5. The device 7 maycomprise any of the well known cumulative ionization discharge apparatuswhich are characterized by a practically instantaneous collapse ofimpedance upon subjection to a potential greater than apredeterminedvalue giving rise to an arc, or in some cases merely a glow discharge,with. consequent rush of current. This apparatus conveniently may takethe form of an envelope containing two electrodes imm'ersec in a usuallyinert, e. g., helium, argon or the like, at a pressure ranging between10 m. m. 1502 c. m. Hg, suiiicicnt to support a glow or arc-likedischarge depending upon the current requirements of the relay andspaced apart a distance such that upon the application of suitablevoltage, discharge takes place in the manner stated.v in the device asillustrated, the electrodes are of similar shape and size, hencesubstantially no rectification of the alternating current wave isproduced although it is obvious that a rectifier may also be used toadvantage in connection with a direct current relay. The respectivecircuits A and B are rendered elec-v trically independent of one anotherexcept for the coupling 5 by means of the equipotential conductor 8. v

Upon the application of suitable voltage to the transformer 1, usuallysupplied from house lighting mains and assuming cell 4 to be acti atedinepp iable ur en eerses the i t 4, a 8 e ause t e mp d ance of thephoto-cell is exceedingly high and hence comparatively no energy istranstuned through the sa pl ng 5 to. the adlacent circuit. Under theseconditions, the voltage applied across the device 7 is so regulated asto reclude substantial discharge between the eectrodes. This voltageordinarily is maintained slightly below the voltage at with. br ak owncc s- H W Y n upe i .QWQHQ. OI the ell 4 by a light $Q ll9 not hostwhichay u rri the head l ght o a, nrcvin vehicle or a predetermined Inteni MQf y gbt 0. ny othe s urc the chang oi which are. designed tov initiatethe centre mpl l et Pi ateen itiv laye emits e dons" and the impedanceofthe cell s great y reduced. resul ng n the l c t'w th o gh. thecoupling 5 of an a p e iah voltage upon circuit 13.. Theadditionalvoltage thu app ed. may b ufli e t to init at a ubsta tiial dscharge ig or p y an are betw n. h eq r de iwh h hug may. p r ist dur nthe m. ming pert ien th half; cy e A e at ve y large cur en is s. va a e01: p tive y we ung he r lay 6. which m y c n ro c ntac s formingportion ex e nal circuit The 1 c rcu t, A may be likened in a broadsense to at? 1: rran em n s reel di n, whi h a r l tivelx ma l v riatiorc fi er y Qngk re Prdduc dby e eeg sm the .1g .ts e i a apted. 9 efiecir y we 1, at ea he mam here n at a heavy ur ent i cliarge, in theadjacen r it 13- FIOI the fates-cine, t e den t a ari u m ha earns Q. tharran emen descr bedwi l. su g t b e ve to. t ose sk led 1 the a t, rsaw .1, the ph t lec e l may e rlaced len um ce wi h uitabl ha e rans qm ve tages al th r ii 6-Way be s' ie t be actua ed o y use rc' t A, is-e e ie d a w t photo-cell isin an inactivated state. More over,depending upon the function of the control. circuits, energy derivedthrough the coupling from circuit A sometimes may be advantageouslyemployed to detract from the energy normally flowing in circuit B; m order to operate a differential: relay.

What. I claim as new and desire to. secure by Letters. Patent of theUnited States, is

1-. Means for controlling. a circuit in re.- sponse to light variations,said means con pnisin a gaseous discharge evice dapt d.- o besubstantially non-Conductive. at voltages el w a predet rmined voltagebut Q Pa s a discharg hav ug rcke chara ter s ics were aid. vol age, aalternating Current source which normall applies a volta across saiddevice insu cient to cause a su stantial discharge therethrough, andmeans including a light-sensitive device for increasing said voltageapplied across said device sufficiently to cause an arc-like dischargeto flow through said device thereby to energize the circuit to becontrolled.

2. An electrical system comprising a source of lt rnating curre tconnected to energize a plurality of circuits, one of said circuitscontaining a light-sensitive device and another of said circuitscontaining in series a cumulativeionizationdevice,anelectromagneticrelay and a member for coupling said lattercircuit tothecirouit containingthe light-sensitive devic said member inreas ng the le tric l en gy in. aid at er r uit, up cti ati n f said, gensi e, e ice, y n e ergy transfer from said circuit containingthelightsensitive device.

3. In combination, a transformer having a multi-sectioned secondary, oneof said sections being adapted to energize a circuit con-v taininglight-sensitive apparatus, another section, being adapted to energize acircuit containing an electrical discharge device, said device beingcharacterized by'the fact that it is substantially conductive only atimpressed "MP L e gre than a m imum d i h a me ly is maintai d at v tags ess han said minimum and means whereby ener is transferred from thecircuit containing the light-sensitive device, upon activation of thelatte by light, to the oth cir u t f r c using the electrical dischargedeyice to be conductive.

4- In. c m inati n, a sourc o al e nat n current, a re ay or contro lingan. a xi iar irc it an means e ially ne t b ween sa d co r e an r l y fr e g zing he-re ay n n nse. t cha ges, a ig t, sa m ans Compr sing each0 an electrical discharge devis ontain ng a pa o p rating e trodesonlyflhc space therebetween constitutins e a yhig mp dan a of a ighensitive dev w ic 11 .1 a ti a ion y ight oopera es w th he e adischarge ev ce o; re u e he mp an e of the et r to. a egree ufi 'oi ntor the n i ti n of a arc discharge whereby the relay is energized;

5 In combination, a plurality of intercom ec ed. c r u t a c mm n o e oa t ing current adapted to energize-said circuits, one of said circuitscontaining light-sensitive pparatus a d anot r ta nin a relay and anelectrical discharge device in series, said device normally beingof'sulficiently high impedance to prevent the relay from operating butbeing adapted upon activation] of the gh n tiye apparatus o a it p easesubsta t a yreduced to n r r si ie i. o Per the ni ati of =1 i ha ge hin a ke hara t st thereby 66 ca s he a tuation of said relay, ancQupling means, external to said electrical discharge device, forcooperating with said light-sensitive circuit and decreasing theimpedance of said electrical discharge device.

In witness whereof I have hereto set my hand this third day of August,1928.

THOMAS A. E. BELT.

